The up-tempo spread attack has appeal, but there are questions to be asked before hiring the Oregon coach.

The idea is undeniably intriguing: Oregon Coach Chip Kelly in the NFL, bringing his up-tempo offense to the highest level.

Sure, it could be a flop of Steve Spurrier-like proportions, a star college coach watching his Saturday system fizzle in such a spectacular way on Sundays. But it could work too, seeing as most NFL teams have some version of a read-option offense in their playbooks. We've seen San Francisco run it with Colin Kaepernick, Seattle run it with Russell Wilson and Washington run it with Robert Griffin III.

So the rumors swirling that several teams are eyeing Kelly aren't that crazy at all. There has been lingering speculation that Kelly could replace Andy Reid in Philadelphia, for instance.

Kelly can evolve and adapt. He has done that successfully with the Ducks. Not every running back has to be a 5-foot-8, 195-pound water bug like LaMichael James. The burly Jonathan Stewart had a stellar career at Oregon and was a first-round pick.

But before any team made the leap to hire Kelly, any clear-headed general manager would have to get some important answers. Among the pertinent questions:

How do you protect the quarterback? The quarterback is much more exposed in Kelly's type of system, particularly when he's carrying the ball. Lots of big hits. We've already seen Griffin go down with a concussion this season. (Yes, we've seen lots of traditional drop-back quarterbacks sustain concussions too. But Kelly's quarterback is going to take more hits.)

How are you going to work with these players? It typically takes at least a couple of years for a coach to overhaul a roster. That means Kelly would need to work with a team's current players, at least in the short term. If he's hired, the real test of genius is how he transforms a 330-pound offensive lineman into a marathoner who can stay on the field for 100 offensive snaps a game. That's some serious conditioning, and we're not talking about a 100-man college roster.

Can your defense handle the workload? Say the offense takes a year or two to get rolling, and maybe leads the league in three-and-outs in the interim. That's entirely possible. That defense is going to be on the field a lot. It would get old fast for a defense if it's skulking back on the field after its offensive counterpart had three quick snaps and a punt.

How do you deal with NFL defensive fronts? Oregon's offensive linemen spread out a bit more, and those wide splits don't hurt the Ducks. Can't do that in the pros, though. NFL defensive linemen are quicker penetrators and extremely disciplined. If they have more room to blow up plays in the backfield, they will.

You do know there are no Tennessee Techs on the schedule, right? A college team might play 13 games, and a lot of those are blowouts that allow for second- and third-stringers to play after halftime. There aren't a lot of those games in the pros, and in the NFL you have a minimum of 20 games, counting those in the preseason, with 45 players. That's roughly 21 players on offense, 21 on defense, and three special-teamers (a long snapper, punter and kicker). If Kelly were to bring his fastbreaking style to the pros — and let's face it, that's a lot of the appeal — he could be filling out his roster with a lot of street free agents by the end of the season.

Upon further … oh, never mind

It was the biggest head-scratcher of the Thanksgiving Day games, a non-call that almost certainly cost the Detroit Lions a victory.

The play in question was an 81-yard touchdown run by Houston's Justin Forsett in the third quarter, a score that counted even though replays showed that two Lions had tackled him and he should have been ruled down.

The problem was, Detroit Coach Jim Schwartz threw his challenge flag. That's unsportsmanlike conduct, because all scoring plays are automatically challenged. What's more, because Schwartz threw the flag before replay officials had a chance to initiate their review, it also wiped out the review process entirely.

The result: Touchdown, Houston. No questions asked.

For further explanation, I turned to Mike Pereira, the former NFL supervisor of officials who's now the officiating analyst for Fox.

First, why the unsportsmanlike call? The NFL is worried about coaches using the challenge flag to manipulate the clock. So there's no throwing the challenge flag if a team is out of challenges or timeouts, or if it's inside of two minutes before the half or end of the game, or if the play is automatically reviewed — which this season includes all scoring plays and turnovers.

But the critical part of Thursday's play was that Schwartz negated any review. How did that happen?

Pereira said the seeds of that rule were sown a couple years ago in a game involving the New York Giants.